[fred@fredo-arch ~]$ valgrind --track-origins=yes ./glxtest
==1989== Memcheck, a memory error detector
==1989== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==1989== Using Valgrind-3.9.0 and LibVEX; rerun with -h for copyright info
==1989== Command: ./glxtest
==1989== 
==1989== Invalid read of size 4
==1989==    at 0x8DBA0BE: nouveau_fence_wait (nouveau_fence.c:205)
==1989==    by 0x8E4AFF4: nv50_screen_destroy (nv50_screen.c:293)
==1989==    by 0x8DAACDE: dri_destroy_screen_helper (dri_screen.c:378)
==1989==    by 0x8DAAD74: dri_destroy_screen (dri_screen.c:388)
==1989==    by 0x8AB13D6: driDestroyScreen (dri_util.c:234)
==1989==    by 0x69A06C1: dri2DestroyScreen (dri2_glx.c:712)
==1989==    by 0x697CFE5: FreeScreenConfigs.isra.3 (glxext.c:208)
==1989==    by 0x697D064: glx_display_free (glxext.c:231)
==1989==    by 0x697D164: __glXCloseDisplay (glxext.c:272)
==1989==    by 0x50569F1: XCloseDisplay (in /usr/lib/libX11.so.6.3.0)
==1989==    by 0x4010BE: glxtest() (in /home/fred/glxtest)
==1989==    by 0x40110A: main (in /home/fred/glxtest)
==1989==  Address 0x67cbaa0 is 16 bytes inside a block of size 48 free'd
==1989==    at 0x4C2999C: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==1989==    by 0x8DB9F73: nouveau_fence_update (nouveau_fence.h:48)
==1989==    by 0x8DBA0BD: nouveau_fence_wait (nouveau_fence.c:203)
==1989==    by 0x8E4AFF4: nv50_screen_destroy (nv50_screen.c:293)
==1989==    by 0x8DAACDE: dri_destroy_screen_helper (dri_screen.c:378)
==1989==    by 0x8DAAD74: dri_destroy_screen (dri_screen.c:388)
==1989==    by 0x8AB13D6: driDestroyScreen (dri_util.c:234)
==1989==    by 0x69A06C1: dri2DestroyScreen (dri2_glx.c:712)
==1989==    by 0x697CFE5: FreeScreenConfigs.isra.3 (glxext.c:208)
==1989==    by 0x697D064: glx_display_free (glxext.c:231)
==1989==    by 0x697D164: __glXCloseDisplay (glxext.c:272)
==1989==    by 0x50569F1: XCloseDisplay (in /usr/lib/libX11.so.6.3.0)
==1989== 
VENDOR
nouveau
RENDERER
Gallium 0.4 on NVA8
VERSION
3.0 Mesa 10.1.0
TFP
TRUE
==1989== 
==1989== HEAP SUMMARY:
==1989==     in use at exit: 22,964 bytes in 87 blocks
==1989==   total heap usage: 3,614 allocs, 3,527 frees, 2,299,201 bytes allocated
==1989== 
==1989== LEAK SUMMARY:
==1989==    definitely lost: 768 bytes in 3 blocks
==1989==    indirectly lost: 0 bytes in 0 blocks
==1989==      possibly lost: 0 bytes in 0 blocks
==1989==    still reachable: 22,196 bytes in 84 blocks
==1989==         suppressed: 0 bytes in 0 blocks
==1989== Rerun with --leak-check=full to see details of leaked memory
==1989== 
==1989== For counts of detected and suppressed errors, rerun with: -v
==1989== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 1 from 1)